One sees them a lot around here, given the town I’m in, but that’s not what I’m talking about.
There’s a Spitzer telescope press release about the possible discovery of the most early stars detected to date. These would be the very first stars to have formed in the universe. Remembering that the universe is 13.7 billion years old, pause for a moment to be impressed by the claim of Kashlinsky, Arendt, Mather and Moseley that these stars appeared less than a billion years after the big bang. You should also read some discussion in John Baez’ recent post. [Update: See remarks from Ned Wright at the end of this post.]
The new milestone on the timeline of the universe’s history, if this is correct, would look roughly as in this image (from the press release):
Extraordinary claims (like this one) require extraordinary evidence, and so there’ll no doubt be a lot more discussion about this result in the Astronomy and Cosmology community (and see the update below). They have had to sift through and substract out the infrared light from all known sources (a hugely tall order) in order to identify the signal from these ancestor stars. Whether they’ve done that right will be the most pressing issue. There’s also the possibility that these are not purely stars that they’re seeing, but in fact black holes. There’s no way to tell from the data.
Exciting stuff, nonetheless.
[Update: Ned Wright posted a comment about a paper of his with Cooray et. al., and also points to some comments on his website. Their work argues that this result is not what it is claimed to be. They take into account certain faint galaxies that have been identified in Hubble surveys. Once you do this, Ned says, it removes the apparent signal that Kashlinsky et. al. have attributed to very early “first light” sources.]
-cvj
With talk of popIII stars, and the previous post about James Brown, i figured Really Old Stars must include Mic Jagger.
Isn’t the Milky Way one of the old galaxies – forming in the first billion years? Yeah, we don’t have baby pictures of it because we’re so close by…
While an example of luminosity is given, I can’t help but think that while gravity had dominated, what would such “lensing” allow us to see what was so far back in time?
Wolf-Rayet stars?
Yes, I’m surprised too. But then we’ve seen a lot more of these NASA PR drives recently, not all of them with genuinely strong science behind them. It is a bit disturbing.
Anybody know if there has been a new policy (or policy-maker) behind the PR offensives?
-cvj
Ah, it’s good to see Ned here. I have a post entry written up expressing my doubts about this press release as well. My bottom line: even if you have eliminated everything you know, that doesn’t eliminate what you don’t know.
I was a little surprised to see this PR at all, given that it doesn’t add a whole lot to the one done in November 2005. I called some folks at Spitzer and found out they did this work on more areas of the sky and at different wavelengths, but all with the same instrument.
I suspect that with JWST this can be done better, deeper, and with higher resolution. Maybe then we’ll find out one way or another for sure.
Thanks Ned! I have updated my post to point directly to your remarks and paper.
Best,
-cvj
You might want to look at http://www.astro.ucla.edu/~wright/cosmolog.htm#18Dec06
When galaxies visible in the HST ACS are masked the IR fluctuation signal goes away [Cooray et al.]. So as usual fluctuations are due to things just barely too faint to catalog and mask, and not to [tex]z > 10[/tex] mystery objects. While the IR background is [tex]\propto \int nL dr[/tex], with [tex]n[/tex] the number density and [tex]L[/tex] the luminosity of the sources, the fluctuations are [tex]\propto \int nL^2 r^{-2} dr[/tex] which diverges for small distance [tex]r[/tex].
Maybe the stars and galaxies need to rely on geometrical explanations? What came before and what came after?
Starshine
I wonder too how they shall tell the difference of the oldest stars even with our current experimental measures of satellites in space?
Black holes don’t need stars to produce fuel for them. I imagine that it would be enough to have lots of unprocessed light elements like hydrogen and helium. I don’t see why stars need be neccessary as a significant percentage of the population int their own right.
I did not take your remark as an insult. I was just puzzled as to what the perceived “line” was, since I was not aware of one. I’m happy to hear that you like the posts.
-cvj
You’re right Clifford! However, I’d like to clarify my point with the following thought… If there were only black holes around without the fuel from popIII stars, then I can’t see how black hole accretion ever could have taken place, especially on a cosmic scale. After all, blackholes need some sort of fuel to induce the process of accretion. Otherwise, the black holes would remain in a dormant state, hence, in a permanent Dark Age. In other words, it seems more likely that black holes–along with the fuel from popIII stars–triggered reionization.
By the way, I was merely pointing out that you tend to post on astronomy topics slightly more often than other high-energy physics bloggers: a tendency which I truly enjoy alot! Please don’t take this comment as an insult. In fact, I was trying to give you a sincere compliment!
Best,
Cynthia
I don’t see what your minds’ eye sees. Why can’t this be powered by accretion phenomena surrounding a black hole just as well as fusion processes in a star. At least to a first approximation, I’m not seeing why the former can’t work.
Huh? Which line? I post on any topic I care about whether it be, in science, physics, mathematics, chemistryh, biology, ….. Actually, I think I’ve posted more on astronomy than any other topic so far. I don’t understand what you mean.
Cheers,
-cvj
I’m a little skeptical about this claim that black holes triggered a full-scale reionization of the Universe. In fact, I image the contrary. In my mind’s eye, a blanket of black holes stretching across the Cosmos could only act to keep the Universe in a state of a permanent Dark Age. However, it seems more plausible that popIII stars and black holes could operate in tandem to generate the second great phase change called reionization: the phase change which induced the brilliant epoch known as “First Light”.
By the way, Clifford, thanks for occasionally stepping out of line and posting on astronomy matters from time to time.;)